Discharges of hazardous materials into the environment have lead to contamination of surface water, soil, and aquifers resulting in potential public health problems and degradation of the land for future use. As used in this specification and appended claims, hazardous materials means chemicals or substances that are either toxic or highly toxic, an irritant, corrosive, a strong oxidizer, a strong sensitizer, combustible, either flammable or extremely flammable, dangerously reactive, pyrophoric, pressure-generating, a compressed gas, a carcinogen, a teratogen, a mutagen, a reproductive toxic agent, suspected of having adverse health effects on humans, or listed or regulated by a government agency as being a hazardous material. For example, the U.S. Environmental Protection Agency (USEPA) has established maximum concentration limits (MCLs) for various hazardous materials in water and soils. For instance, stringent drinking water limits placed on many solvent organic compounds in water can be as low as 0.005 mg/L (parts per billion).
In some cases, subsurface groundwater contaminant plumes having hazardous materials may extend hundreds to thousands of feet from the source of a release of the hazardous material into the environment. These hazardous materials may then be transported into drinking water sources, lakes, rivers, and even basements of homes. The presence of hazardous materials in subsurface soils, surface soils, surface water, and groundwater is a well-documented and extensive problem. The source of these hazardous materials is often times from industry where the hazardous materials are released onto the soil surface or surface water or even into the subsurface soil and/or groundwater through leaking storage tanks. Many, if not most, of these hazardous materials are capable of moving through the soil under the influence of moving water, gravity, or capillary action and serve as a source of groundwater contamination. As used in this specification and appended claims, soil is to be interpreted broadly to include all naturally occurring material found at or below ground surface (e.g. silts, clays, sands, rock, karsts, organics, tills, etc.).
Soil, surface water, groundwater, and wastewater can become contaminated with a variety of hazardous materials, organic and inorganic. For example, the environment may become contaminated with volatile, semi-volatile, and non-volatile organic compounds such as PCBs, gasoline, oils, wood preservative wastes, and other hazardous materials. Such other hazardous materials may include, but not limited to, chlorinated solvents (such as trichloroethylene (TCE), vinyl chloride, tetrachioroethylene (PCE), dichloroethanes), ethylene dibromide, halobenzenes, polychlorinated biphenyls, acetone, ter-butyl alcohol, tert-butyl formate, and anilines. Additional contaminants include compounds containing at least one oxidizable aliphatic or aromatic compound and/or functional group (e.g. atrazine, benzene, butyl mercaptan, chlorobenzene, chloroethylvinyl ether, chloromethyl methyl ether, chlorophenol, chrysene, cyanide ion or organic cyanides, dichlorophenol, dichlorohenzene, dichloroethane, dichloroethene, dichloropropane, dichloropropene, ethyl alcohol, ethylbenzene, ethylene glycol, ethyl mercaptan, hydrogen sulfide, isopropyl alcohol, Lindane™, methylene chloride, methyl tert-butyl ether, naphthalene, nitrobenzene, nitrophenol, pentachlorophenol, phenanthrene, phenol, propylene, propylene glycol, Silvex™, Simazine™, sodium sulfide, tetrachloroethane, tetrachloroethene, toluene, trichlorobenzene, trichloroethane, trichloroethene, trichlorophenol, vinyl chloride, xylene, etc). Inorganic hazardous materials may include metals and substances having a mineral origin.
Contaminated soil, surface water and groundwater may need to be removed or treated to make it less toxic or to meet regulatory requirements. There are a variety of reactants and methods for treating contaminated soil, surface water, groundwater, and wastewater. For example, peroxydisulfates may be used for carbon digestion or decomposition. Application methods include thermally activated persulfate oxidation in conjunction with an electro-osmosis system to heat and transport persulfate anions into soils. Permanganate(s) and peroxygen(s) reactant(s) may also be applied constituents for oxidation of materials. Peroxygen compound(s) applied independently or in conjunction with a metallic salt catalyst(s) (complexed and not complexed; chelated and not chelated) may break down materials within the soil, groundwater, and wastewater and make it less toxic, or non-toxic.
Treatment methods of groundwater and subsurface soil include injection of reactant(s), with or without a catalyst(s), and the installation of permeable reactive barriers (PRB). Installation of a PRB may include excavation of a trench at or beyond a subsurface plume of organic and/or inorganic contaminant(s). The trench may be filled with reactant(s) and optionally a permeable media(s) (i.e. sand) for the plume to flow through for a reaction with the hazardous materials.
Another treatment method of groundwater and subsurface soil may include boring one or more boreholes and placing reactant(s) into the boreholes. A plurality of selectively placed boreholes may provide for the installation of a PRB. For example, one or more boreholes may be placed just down flow of a plume of contamination. The boreholes may be charged with reactant(s) directly or a tube or pipe configured to permit flow of water through a circumferential surface thereof may be placed into the borehole(s). The tube or pipe may be porous or otherwise permeable, such as tubing or pipe having perforations, slots, or other openings therein configured to provide the flow of water through the wall of the tubes or pipes.
It may be desired to provide shaped or sized encapsulated reactant(s) for the treatment of materials.